JP2006124513A - Viscosity index improver composition and lubricant composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a viscosity index improver composition more excellent in oxidation stability than a conventional polymethacrylate viscosity index improver composition. <P>SOLUTION: The viscosity index improver composition comprises a polymer (A) containing an alkyl (meth)acrylate (a) with a 1 to 30C alkyl as an essential constituent monomer and a diluent (B), wherein (B) is a diluent containing not more than 0.5 mass% sulfur based on the mass of (B). The lubricant composition comprises the viscosity index improver composition and a base oil. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a viscosity index improver composition. Specifically, the present invention relates to a viscosity index improver composition containing a diluent having a sulfur content of 0.5% by mass or less and a poly (meth) acrylate polymer and a lubricating oil composition containing the same.

Conventionally, when a lubricating oil composition is produced by adding a viscosity index improver to a lubricating base oil, the viscosity index improver has a high viscosity. Therefore, a diluted solution obtained by diluting the viscosity index improver with a diluent is usually added. There was much to do (patent document 1). However, the lubricating oil composition obtained by adding these diluents does not have sufficient oxidation stability, and even when an antioxidant or a dispersant is added, it is not satisfactorily improved.
Japanese Unexamined Patent Publication No. 7-62372

  An object of the present invention is to provide a viscosity index improver composition that does not decrease the oxidation stability of a lubricating oil composition even when added to a lubricating base oil.

As a result of intensive studies, the present inventors have found that a viscosity index improver composition comprising a polymer composed of a diluent having a low sulfur content and a specific monomer is added to a lubricating base oil. It has been found that the oil composition is excellent in oxidation stability, and has led to the present invention.
That is, the present invention is based on the polymer (A) having the alkyl group (meth) acrylic acid alkyl ester (a) having 1 to 30 carbon atoms as the essential constituent monomer and the sulfur content based on the mass of the diluent. A viscosity index improver composition containing a diluent (B) that is 0.5% by mass or less and a lubricating oil composition containing the viscosity index improver composition

  Since the lubricating oil composition using the viscosity index improver composition of the present invention is superior in oxidation stability as compared with the conventional lubricating oil composition, it can meet the demand for extending the life of the lubricating oil composition.

The viscosity index improver composition of the present invention comprises a polymer (A) and a diluent (B), and the sulfur content of (B) is in the following range.
The sulfur content of (B) is usually 0.5% by mass or less based on the mass of (B), preferably 0.1% or less (unless otherwise specified,% represents mass%), particularly preferably Is 0.01% or less. If it exceeds 0.5%, the oxidation stability becomes poor. In addition, the sulfur content of (B) is measured by the high frequency inductively coupled plasma emission spectrometry, and is obtained by the calibration curve method.

As the diluent (B) in the present invention,
Aliphatic solvent [C6-C18 aliphatic hydrocarbon (such as hexane, heptane, cyclohexane, octane, decalin and kerosene)];
Aromatic solvent [aromatic solvent having 7 to 15 carbon atoms {toluene, xylene, ethylbenzene and aromatic mixed solvent having 9 carbon atoms (mixture of trimethylbenzene and ethyltoluene)}, aromatic mixed solvent having 10 to 11 carbon atoms Such];
Mineral oils [eg, solvent refined oils, paraffin oils, isoparaffin-containing and / or hydrocracked high viscosity index oils, naphthenic oils]; and synthetic lubricating oils [hydrocarbon synthetic lubricating oils (polyalphaolefin synthetic lubricating oils] ), Ester-based synthetic lubricating oils]; among these, mineral oils are preferred.
In the present invention, the lower limit of the proportion of (B) contained in the viscosity index improver composition is preferably 10%, more preferably 30%, particularly preferably 40%, based on the mass of (A). Is preferably 900%, more preferably 800%, particularly preferably 600% based on the mass of (A).
A higher ratio of (B) is preferable in that it is easily dissolved in the base oil, but too much is not economical.

(B) in the present invention has a kinematic viscosity at 100 ° C. of usually 1 to 15 mm ² / s, preferably ² to 6 mm ² / s, and is usually 70 or more, preferably 100 or more, more preferably 105 to 180. Having a viscosity index of The lubricating oil to which the viscosity index improver composition containing (B) is added has a higher viscosity index and good fuel economy.

The following (a1) to (a5) may be mentioned as the (meth) acrylic acid alkyl ester (a) having 1 to 30 carbon atoms in the alkyl group, which is an essential constituent monomer of the polymer (A).
(A1) C1-C4 (meth) acrylic acid alkyl ester of alkyl group:
For example, methyl acrylate, methyl methacrylate (hereinafter abbreviated as MMA), ethyl (meth) acrylate, n- or iso-propyl (meth) acrylate, n-, iso- or sec-butyl (meth) acrylate Preferred are methyl methacrylate and n-butyl methacrylate.

(A2) (meth) acrylic acid alkyl ester having 8 to 15 carbon atoms (linear and / or branched) of the alkyl group:
For example, n-octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-decyl (meth) acrylate, n-isodecyl (meth) acrylate, n-undecyl (meth) acrylate, (meth) N-dodecyl acrylate, 2-methylundecyl (meth) acrylate, n-tridecyl (meth) acrylate, 2-methyldodecyl (meth) acrylate, n-tetradecyl (meth) acrylate, (meth) acrylic acid 2-methyltridecyl, n-pentadecyl (meth) acrylate, 2-methyltetradecyl (meth) acrylate, alcohol produced by oxo synthesis [e.g., trade name "DOBANOL 23" (manufactured by Mitsubishi Chemical Corporation), "TRIDECanol ”(Manufactured by Kyowa Hakko),“ Oxocol 1213 ”(manufactured by Nissan Chemical),“ Dovanol 45 ”(manufactured by Mitsubishi Chemical), (Meth) acrylic acid ester with “Oxocol 1415” (manufactured by Nissan Chemical Co., Ltd.) and the like (hereinafter, methacrylic acid ester with “Dovanol 23” is abbreviated as D23, and methacrylic acid ester with “Dovanol 45” is abbreviated as D45) . Among these, (meth) acrylic acid alkyl esters having a linear and / or branched alkyl group having 12 to 15 carbon atoms are preferred.

(A3) Alkyl ester of (meth) acrylic acid having 16 to 24 carbon atoms (straight and / or branched) of the alkyl group:
For example, n-hexadecyl acrylate, n-hexadecyl methacrylate (hereinafter abbreviated as HMA), n-octadecyl acrylate, n-octadecyl methacrylate (hereinafter abbreviated as OMA), n-eicosyl (meth) acrylate, (meth) acrylic N-docosyl acid, 2-methylpentadecyl (meth) acrylate, 2-hexyldecyl (meth) acrylate, 2-methylhexadecyl (meth) acrylate, 2-octyldecyl (meth) acrylate, (meth) 2-hexyldecyl acrylate, 2-methylheptadecyl (meth) acrylate, 2-methyloctadecyl (meth) acrylate, 2-octyldodecyl (meth) acrylate, 2-decyltetradecyl (meth) acrylate, etc. Of these, preferred are straight chain alkyl groups having 16 to 18 carbon atoms. (Meth) acrylic acid alkyl ester and (meth) acrylate, 2-decyl tetradecyl.

(A4) an alkyl group having 5 to 7 carbon atoms (straight and / or branched) (meth) acrylic acid alkyl ester:
(Meth) acrylic acid n-, iso-, sec- and neopentyl (meth) acrylic acid, hexyl, heptyl (meth) acrylate, and the like.
Preferred among (a) are (a1) to (a3) and combinations of two or more thereof.

  In the polymer (A), the following (d) to (n) may be mentioned as monomers that can be used in addition to (a).

(D) a nitrogen atom-containing monomer;
(D1) Nitro group-containing monomer:
For example, 4-nitrostyrene

(D2) A primary to tertiary amino group-containing vinyl monomer:
Primary amino group-containing vinyl monomer, for example, alkenylamine having 3 to 6 carbon atoms [(meth) allylamine, crotylamine, etc.], aminoalkyl (2 to 6 carbon atoms) (meth) acrylate [aminoethyl (meth) acrylate Etc.] Secondary amino group-containing vinyl monomer, for example, alkyl (C1-6) aminoalkyl (C2-6) (meth) acrylate [t-butylaminoethyl methacrylate, methylaminoethyl (meth) Acrylate etc.], diphenylamine (meth) acrylamide [4-diphenylamine (meth) acrylamide, 2-diphenylamine (meth) acrylamide etc.], C6-C12 dialkenylamine [di (meth) allylamine etc.], tertiary amino group Containing vinyl monomer, for example, dialkyl (1 to 4 carbon atoms) Aminoalkyl (2 to 6 carbon atoms) (meth) acrylate [dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, etc., dialkyl (1 to 4 carbon atoms) aminoalkyl (2 to 6 carbon atoms) (meth) Acrylamide [dimethylaminoethyl (meth) acrylamide, diethylaminoethyl (meth) acrylamide, dimethylaminopropyl (meth) acrylamide, etc.], tertiary amino group-containing aromatic vinyl monomer [N, N-dimethylaminostyrene, etc.] , Nitrogen-containing heterocyclic ring-containing vinyl monomers [morpholinoethyl (meth) acrylate, 4-vinylpyridine, 2-vinylpyridine, N-vinylpyrrole, N-vinylpyrrolidone, N-vinylthiopyrrolidone, etc.]

(D3) Quaternary ammonium base-containing vinyl monomer:
For example, the above-mentioned tertiary amino group-containing vinyl monomer is quaternized with a quaternizing agent (alkyl chloride having 1 to 12 carbon atoms, dialkyl sulfuric acid, dialkyl carbonate, benzyl chloride, etc.). Can be mentioned. Specifically, examples of the alkyl (meth) acrylate quaternary ammonium salt include (meth) acryloyloxyethyltrimethylammonium chloride, (meth) acryloyloxyethyltriethylammonium chloride, and (meth) acryloyloxyethyldimethylbenzylammonium. Chloride, (meth) acryloyloxyethylmethylmorpholino ammonium chloride and the like; alkyl (meth) acrylamide quaternary ammonium salts include, for example, (meth) acryloylaminoethyltrimethylammonium chloride, (meth) acryloylaminoethyltriethylammonium chloride, (Meth) acryloylaminoethyldimethylbenzylammonium chloride, etc .; other quaternary ammonium salts The containing vinyl monomers, for example, dimethyl diallyl ammonium methyl sulfate, etc. trimethyl vinylphenyl ammonium chloride,

(D4) Amphoteric vinyl monomer:
N- (meth) acryloyloxy (or amino) alkyl (C1-10) N, N-dialkyl (C1-5) ammonium-N-alkyl (C1-5) carboxylate (or sulfate), For example, N- (meth) acryloyloxyethyl N, N-dimethylammonium N-methylcarboxylate, N- (meth) acryloylaminopropyl N, N-dimethylammonium N-methylcarboxylate, and N- (meth) acryloyloxy Ethyl N, N-dimethylammonium propyl sulfate, etc.

(D5) Nitrile group-containing monomer:
(Meth) acrylonitrile, etc.

(E) Aliphatic hydrocarbon vinyl monomer:
For example, alkenes having 2 to 20 carbon atoms [ethylene, propylene, butene, isobutylene, pentene, heptene, diisobutylene, octene, dodecene, octadecene, etc.] and alkadienes having 4 to 12 carbon atoms [butadiene, isoprene, 1,4- Pentadiene, 1,6-heptadiene, 1,7-octadiene, etc.]

(F) Alicyclic hydrocarbon vinyl monomer:
For example, cyclohexene, (di) cyclopentadiene, pinene, limonene, indene, vinylcyclohexene, and ethylidenebicycloheptene, etc.

(G) Aromatic hydrocarbon vinyl monomer:
For example, styrene, α-methylstyrene, vinyltoluene, 2,4-dimethylstyrene, 4-ethylstyrene, 4-isopropylstyrene, 4-butylstyrene, 4-phenylstyrene, 4-cyclohexylstyrene, 4-benzylstyrene, 4 -Crotylbenzene, 2-vinylnaphthalene, etc.

(H) Vinyl esters, vinyl ethers, vinyl ketones:
For example, vinyl esters of saturated fatty acids having 2 to 12 carbon atoms [vinyl acetate, vinyl propionate, vinyl butyrate, vinyl octoate, etc.], alkyl ethers having 1 to 12 carbon atoms, aryl or alkoxyalkyl vinyl ethers [methyl vinyl ether, ethyl vinyl ether , Propyl vinyl ether, butyl vinyl ether, 2-ethylhexyl vinyl ether, phenyl vinyl ether, vinyl 2-methoxyethyl ether, vinyl 2-butoxyethyl ether, etc.], and alkyl or aryl vinyl ketones having 1 to 8 carbon atoms [methyl vinyl ketone, ethyl vinyl] Ketone, phenyl vinyl ketone, etc.],

(I) an epoxy group-containing vinyl monomer;
For example, glycidyl (meth) acrylate glycidyl (meth) allyl ether, etc.

(J) a halogen element-containing vinyl monomer;
For example, vinyl chloride, vinyl bromide, vinylidene chloride, (meth) allyl chloride, halogenated styrene (dichlorostyrene, etc.)

(K) an ester of an unsaturated polycarboxylic acid;
Examples thereof include alkyl, cycloalkyl or aralkyl esters of unsaturated polycarboxylic acids, and among them, alkyl diesters having 1 to 8 carbon atoms of unsaturated dicarboxylic acids [maleic acid, fumaric acid, itaconic acid, etc.] [dimethyl maleate, Dimethyl fumarate, diethyl maleate, dioctyl maleate]

(L) a hydroxyl group-containing vinyl monomer;
For example, hydroxyl group-containing aromatic vinyl monomer [p-hydroxystyrene etc.], hydroxyalkyl (2 to 6 carbon atoms) (meth) acrylate [2-hydroxyethyl (meth) acrylate, 2 or 3-hydroxypropyl (meta) ) Acrylates, etc.], mono- or di-hydroxyalkyl (1 to 4 carbon atoms) substituted (meth) acrylamide [N, N-dihydroxymethyl (meth) acrylamide, N, N-dihydroxypropyl (meth) acrylamide, N, N -Di-2-hydroxybutyl (meth) acrylamide etc.], vinyl alcohol (formed by hydrolysis of vinyl acetate unit), C3-C12 alkenol [(meth) allyl alcohol, crotyl alcohol, isocrotyl Alcohol, 1-octenol, 1-undece Etc.], C 4-12 alkene diol [1-buten-3-ol, 2-buten-1-ol, 2-butene-1,4-diol etc.], hydroxyalkyl (C 1-6 ) Alkenyl (3 to 10 carbon atoms) ether [2-hydroxyethylpropenyl ether and the like], polyhydric (3 to 8 valent) alcohol (alkane polyol, intramolecular or intermolecular dehydrated product, saccharide such as glycerin, pentaerythritol, Alkitol (3 to 10 carbon atoms) ether or (meth) acrylate [sucrose (meth) allyl ether] of sorbitol, sorbitan, diglycerin, sucrose,

(M) a polyoxyalkylene chain-containing vinyl monomer;
For example, polyoxyalkylene glycol (alkylene group having 2 to 4 carbon atoms, degree of polymerization 2 to 50), or polyoxyalkylene polyol [polyoxyalkylene ether of 3 to 8 valent alcohol (alkyl group having 2 to 4 carbon atoms) , Degree of polymerization 2-100)], or mono (meth) acrylates thereof (polyethylene glycol (molecular weight 100-300) mono (meth) acrylate, polypropylene glycol (molecular weight 130-500) Mono (meth) acrylate, methoxypolyethylene glycol (molecular weight 110-310) (meth) acrylate, lauryl alcohol ethylene oxide adduct (2-30 mol) (meth) acrylate, mono (meth) acrylic acid polyoxyethylene (molecular weight 150-230 Sorbitan], etc.,

(N) a carboxyl group-containing vinyl monomer;
Monocarboxyl group-containing vinyl monomers such as unsaturated monocarboxylic acids [(meth) acrylic acid, α-methyl (meth) acrylic acid, crotonic acid, cinnamic acid, etc.], monoalkyls of unsaturated dicarboxylic acids (carbon number) 1-8) Esters [maleic acid monoalkyl esters, fumaric acid monoalkyl esters, itaconic acid monoalkyl esters, etc.]; vinyl monomers containing two or more carboxyl groups, such as maleic acid, fumaric acid, itaconic acid Citraconic acid and the like.

  Among these monomers (d) to (n), preferred are (d), (l) and a combination thereof, more preferred is (d), particularly preferred is (d2), and particularly preferred. Are dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate (hereinafter abbreviated as DAE), diethylaminoethyl (meth) acrylate and morpholinoethyl (meth) acrylate.

  The proportion of (a1) in the monomer constituting (A) is usually 0%, preferably 5%, more preferably 10%, the lower limit from the viewpoint of viscosity index and solubility in base oil, and the upper limit. Is preferably 45%, more preferably 40%, particularly preferably 35%, particularly preferably 25%, most preferably 22%.

  The lower limit of the proportion of (a2) is preferably 0.1%, more preferably 20%, particularly preferably 30%, particularly preferably 40%, most preferably 50, from the viewpoint of viscosity index and solubility in base oil. The upper limit is usually 100%, preferably 95%.

  From the viewpoint of the viscosity index and the low temperature viscosity, the lower limit is usually 0%, preferably 5%, and the upper limit is preferably 75%, more preferably 65%, particularly preferably 50%, particularly preferably. 20%.

  The proportion of (d) in the monomer constituting (A) is usually 0% at the lower limit, preferably 0.1%, more preferably 1%, particularly preferably 2%, from the viewpoint of sludge dispersibility. The upper limit is preferably 10%, more preferably 7%, and particularly preferably 5%.

  The preferred combinations of the ratios (a1), (a2) and (a3) in (A) are (a1) 0 to 45%, (a2) 0.1 to 100% and (a3) 0 to 0%. More preferred combinations are 5 to 40% for (a1), 20 to 95% for (a2) and 5 to 65% for (a3).

The weight average molecular weight (hereinafter abbreviated as Mw) of (A) is preferably 5,000 to 1,000,000, more preferably 15,000 to 500,000, and particularly preferably 20,000 to 100,000. It is. Mw in the present invention is measured by gel permeation chromatography using polystyrene as a standard.
As a means for adjusting Mw, it can be adjusted by, for example, the temperature at the time of polymerization described later, the monomer concentration (diluent concentration), the amount of catalyst and the amount of chain transfer agent.

The viscosity index improver composition of the present invention contains one composition or one Mw (A), or two or more compositions and / or two or more Mw (A) is contained.
From the viewpoint of low-temperature viscosity, a viscosity index improver composition containing 2 or more types (A), particularly 2 or more types of (A) is preferred.

A preferred combination in the case of containing (A) having two or more kinds of compositions is a polymer (A1) having (a2) as an essential constituent monomer and optionally (a1) and / or (a3) as a constituent monomer. ) And a polymer (A2) having (a2) as an essential constituent monomer and optionally (a3) as a constituent monomer.
The mass ratio of the monomers constituting (A1) is preferably (a1) / [(a2) + (a3)] = (5-30) / (95-70), more preferably (10-22) / (90-78).
A preferable configuration of the monomer in (A2) includes at least one of the monomers having 12 to 18 carbon atoms and an average carbon number of 12 to 16.
A preferable mass ratio of the mass ratio (A1) / (A2) is (99 to 85) / (1 to 15) from the viewpoint of low temperature viscosity.

As a specific example of (A) in the case of containing two or more types (A),
(A1); For example, methyl methacrylate / alkyl group having 12 to 15 carbon atoms / methacrylic acid ester having 16 to 20 carbon atoms of alkyl group (0 to 22% / 20 to 90% / 0 to 20%) Copolymer, etc.
(A2); for example, dodecyl methacrylate / hexadecyl methacrylate (10 to 50% / 50 to 90%) copolymer [average carbon number: 14.0 to 15.6], dodecyl methacrylate / tetradecyl methacrylate (90 to 70% / 10-30%) copolymer [average carbon number: 12.2-12.6], and D23 / HMA / OMA (30-70% / 5-50% / 3-20%) copolymer [Average carbon number: 13.7 to 15.4].

(A) can be obtained by a known production method. For example, the monomer can be obtained by radical polymerization in the presence of a polymerization catalyst by using the diluent (B) as necessary.
The use ratio of (B) is usually 5 to 80%, preferably 10 to 60% based on the total mass of the monomers.
Examples of the polymerization catalyst include azo catalysts (for example, 2,2′-azobisisobutyronitrile, 2,2′-azobis (2-methylbutyronitrile) (hereinafter abbreviated as AMBN), 2,2′-azobis. (2,4-dimethylvaleronitrile) (hereinafter abbreviated as ADVN), dimethyl 2,2-azobisisobutyrate, etc.) and peroxides (eg, t-butyl peroxypivalate, t-hexyl peroxypi) Valate, t-butyl peroxyneoheptanoate, t-butyl peroxyneodecanoate, t-butyl peroxy 2-ethylhexanoate, t-butyl peroxyisobutyrate, t-amyl peroxy 2- Ethylhexanoate, 1,1,3,3-tetramethylbutylperoxy 2-ethylhexanoate, dibutylperoxytrimethyladipate, Emissions benzoyl peroxide, cumyl peroxide, lauryl peroxide, benzoyl peroxide, cumyl peroxide, lauryl peroxide) can be used.
Furthermore, if necessary, a chain transfer agent may be used in combination. Examples of such a chain transfer agent include thiocarboxylic acids (n-lauryl mercaptan (hereinafter abbreviated as DM), mercaptoethanol, mercaptopropanol, etc.), thiolic acids (thioglycolic acid). , Thiomalic acid, etc.), amines (dibutylamine, etc.) and the like. The amount of the chain transfer agent is preferably 0.001 to 5%, more preferably 0.05 with respect to the mass of the monomer. ~ 3%. The reaction temperature is 50 to 140 ° C, preferably 70 to 120 ° C. In addition to solution polymerization using the above diluent, it can also be obtained by bulk polymerization, emulsion polymerization or suspension polymerization. Further, the polymerization mode when (A) is a copolymer may be any of random copolymerization, alternating copolymerization or block copolymerization, and (A) may be either linear or branched.

Production of the viscosity index improver composition of the present invention,
(1) A method in which a monomer is polymerized in the presence of (B) or, if necessary, further diluted with (B).
(2) A method of diluting with (B) later without using (B) during polymerization.
Etc. The method (1) is preferable from the viewpoint of handling.

The viscosity index improver composition of the present invention may contain other additives. Other additives include pour point depressants (eg, alkyl naphthalene, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, α-olefin copolymer, alkenyl succinic acid amide, etc.), detergents (sulfonates) , Salicylate-type, phenate-type, naphthenate-type Ca and Mg salts, calcium carbonate), dispersant (succinimide-type; histyp, monotype, borate-type, Mannich condensate type, etc.), antioxidant (zincji Thiophosphate, amine type; diphenylamine, hindered phenol type, zinc thiophosphate, trialkylphenol, etc., oiliness improver (long chain fatty acid type; oleic acid, long chain fatty acid ester; oleic acid ester, long chain amine type: oleylamine, etc. , Long chain amide; oleamide), friction wear Agents (molybdenum dithiophosphate, molybdenum carbamate, zinc dialkyldithiophosphate, etc.), extreme pressure agents (sulfur phosphorus, sulfur, phosphorus, chlor, etc.), defoamers (silicone oil, metal soap, fatty acid ester, phosphorus) Acid esters, etc.), demulsifiers (quaternary ammonium salts, sulfated oils, phosphate esters), and corrosion inhibitors (nitrogen compounds such as benzotriazole, 1,3,4-thiodiazolyl-2,5-bisdialkyldithiocarbamate And sulfur- and nitrogen-containing compounds).
The amount of other additives based on the mass of the viscosity index improver composition is 0-20% for pour point depressants, preferably 0.1-10%, more preferably 0.1-5%, detergents. 0-30%, preferably 0.1-20%, dispersant 0-30%, preferably 0.2-20%, antioxidant 0-10%, preferably 0.1-2%, oiliness improvement 0 to 5%, preferably 0.1 to 2%, friction wear modifier 0 to 5%, preferably 0.1 to 3%, extreme pressure agent 0 to 40%, preferably 0.1 to 10% The antifoaming agent is 2-1000 ppm, preferably 10-700 ppm, the demulsifier is 0-3%, preferably 0-1%, and the corrosion inhibitor is 0-3%, preferably 0-2%.
The total amount of other additives based on the mass of the viscosity index improver composition is usually 0 to 50%, preferably 0 to 30%, more preferably 0 to 20%.
The ratio of (A) / (B) / other additives in the lubricating oil additive composition of the present invention is usually 30-80 / 70-20 / 0-50, preferably 40-75 / 60-25 /. It is 0-30, More preferably, it is 50-75 / 50-25 / 0-20.

The lubricating oil composition of the present invention contains the above viscosity index improver composition and a base oil.
The cloud point (JIS K2269-1993) of the base oil is preferably −5 ° C. or lower. More preferably, it is −15 ° C. to −60 ° C. When the cloud point of the base oil is within this range, the low temperature viscosity of the lubricating oil composition obtained with a small amount of wax precipitation is good. Base oils include solvent refined oils, high viscosity index oils containing isoparaffins and / or hydrocracking, hydrocarbon synthetic lubricating oils (polyalphaolefin synthetic lubricating oils), ester synthetic lubricating oils, naphthenic oils, etc. Can be mentioned. Of these, high viscosity index oils containing isoparaffins and / or hydrocracking are preferred.

  The lubricating oil composition of the present invention preferably contains 0.5 to 30% as (A) based on the mass of the base oil.

When the lubricating oil composition is engine oil, 0.5 to 15% is preferably added as (A) based on the mass of the base oil having a kinematic viscosity at 100 ° C. of 3 to 10 mm ² / s. .
In the case of gear oil, 3 to 30% is preferably added as (A) based on the mass of the base oil having a kinematic viscosity at 100 ° C. of 3 to 10 mm ² / s.
In the case of automatic transmission oil (ATF, belt CVT oil), it is preferable to add 2 to 25% as (A) based on the mass of the base oil having a kinematic viscosity at 100 ° C. of ² to 6 mm ² / s. .
In the case of traction oil, 0.5 to 15% is preferably added as (A) based on the mass of the base oil having a kinematic viscosity at 100 ° C. of 1 to 5 mm ² / s.
In the case of hydraulic oil, 0.5 to 25% is preferably added as (A) based on the mass of the base oil having a kinematic viscosity at 100 ° C. of 1 to 10 mm ² / s.

  The lubricating oil composition of the present invention is used for engine oil, gear oil, automatic transmission oil (ATF, CVT oil), traction oil, shock absorber oil, power steering oil, etc. for transportation equipment and various machine tools.

<Example>
The present invention will be described in detail below with reference to examples, but the present invention is not limited thereto. In addition, the part in an Example and a comparative example represents a mass part.

Examples 1-3 and Comparative Example 1;
A reaction vessel equipped with a stirrer, heating / cooling device, thermometer, dropping funnel, and nitrogen blowing tube was charged with 25 parts of the following mineral oil as a diluent during polymerization, and listed in Table 1 in another glass beaker. 100 parts in total, 2,2′-azobis (2,4-dimethylvaleronitrile: abbreviated as ADVN) as a radical polymerization initiator, and DM as a chain transfer agent in the amounts shown in Table 1, were charged at 20 ° C. The monomer solution was prepared by stirring and mixing at, and charged into the dropping funnel. After carrying out nitrogen substitution of the gas phase part of the reaction vessel, the monomer solution was added dropwise at 85 ° C. for 4 hours in a sealed state, and after aging at 85 ° C. for 2 hours from the end of the addition, reduced pressure at 130 ° C. for 3 hours. The following additional diluent 42 parts are added to 125 parts of the polymer obtained by removing the low boiling point component below to dilute, and viscosity index improver compositions (A-1) to (A-3) and ( X-1) was obtained.
In Examples 1 to 3, Diana Fresia K-8 (mineral oil; sulfur content = 0.01 mass%, 100 ° C. kinematic viscosity = 2.3 mm ² / s, viscosity index = 78; manufactured by Idemitsu Kosan Co., Ltd.), and Comparative Example 1, Diana Fresia U-46 (mineral oil; sulfur content = 0.94% by mass, kinematic viscosity at 100 ° C. = 5.540 mm ² / s, viscosity index = 27; manufactured by Idemitsu Kosan Co., Ltd.) diluent and addition during polymerization Diluent.

Examples 4-7 and Comparative Example 2;
Base oil (kinematic viscosity at 100 ° C .: 3.0 mm ² / s, viscosity index: 117, cloud point: −23 ° C., sulfur content = 0.01% by mass or less) using a stainless steel container equipped with a stirring and mixing device. (A-1) to (A-3) and (X-1) were blended in the amounts shown in Table 2 and dissolved.
Table 2 shows the results of evaluating the oxidation stability of the resulting lubricating oil composition.

(Method of oxidation stability test)
The test conditions of the test method specified in JIS-K-2514 were changed to 130 ° C. and 72 hours. And the pentane insoluble part of the lubricating oil composition after a test was calculated | required by A method of JPI-5S-18-80. It shows that it is excellent in oxidation stability, so that a value is small.

  The lubricating oil composition using the viscosity index improver composition of the present invention is superior in oxidative stability compared to a lubricating oil composition using a conventional PMA viscosity index improver composition. It can meet the demand for longer life of oil. Therefore, drive system lubricating oil (manual transmission oil, differential gear oil, automatic transmission oil, belt CVT oil, etc.), hydraulic oil (machine hydraulic oil, power steering oil, shock absorber oil, etc.), engine oil (for gasoline, diesel) And the like, and can be suitably used for traction oil.

Claims (7)

  Viscosity index improver composition comprising a polymer (A) comprising a (meth) acrylic acid alkyl ester (a) having an alkyl group having 1 to 30 carbon atoms as an essential constituent monomer and a diluent (B) A viscosity index improver composition, wherein (B) is a diluent containing 0.5% by mass or less of sulfur based on the mass of (B). The viscosity index improver composition according to claim 1, wherein the diluent (B) has a kinematic viscosity at 100 ° C of 1 to 15 mm ² / s and a viscosity index of 70 or more.   The polymer (A) is a (meth) acrylic acid alkyl ester (a1) having 1 to 4 carbon atoms in the alkyl group, a (meth) acrylic acid alkyl ester (a2) and alkyl having 8 to 15 carbon atoms in the alkyl group. The (meth) acrylic acid alkyl ester (a3) having 16 to 24 carbon atoms is used as a constituent monomer, and the proportion of (a1) is 0 to 45% by mass based on the total mass of the monomers, (a2) The viscosity index improver composition according to claim 1 or 2, wherein the ratio of is 0.1 to 100 mass% and the ratio of (a3) is 0 to 75 mass%.   The viscosity index improver composition according to any one of claims 1 to 3, comprising two or more different types (A).   The viscosity index improver composition according to any one of claims 1 to 4, wherein the ratio of the diluent (B) based on the mass of the polymer (A) is 10 to 900 mass%.   Furthermore, the viscosity index improver composition in any one of Claims 1-5 formed by containing another additive.   A lubricating oil composition comprising the viscosity index improver composition according to any one of claims 1 to 6 and a base oil.